Field of the Invention
The present embodiments relate to an image forming apparatus, such as a copying machine, a printer, and a facsimile, in which an exterior cover is opened and closed and a process cartridge mounted inside the apparatus is removed or replaced.
Description of the Related Art
In a certain configuration, an image bearing member (photosensitive drum) with a toner image formed thereon and an image forming unit (developing roller) are configured as a cartridge removably mounted on an image forming apparatus main body (apparatus main body), facilitating the replacement of consumables and other maintenance works.
With this cartridge of contact development type, development is performed by bringing the photosensitive drum into contact with the developing roller at the time of image formation. From the viewpoint of the life of a photosensitive drum and a developing roller, the contact development type is configured so that a pressing member of the apparatus main body presses a development container of the cartridge to switch the photosensitive drum and the developing roller between a contact state and a separation state.
Japanese Patent Application Laid-Open No. 2013-246247 discusses two different processes for mounting a cartridge in an apparatus main body: a process for moving the cartridge in the axial direction of a photosensitive drum (insertion process), and a process for moving the cartridge having a directional component perpendicularly intersecting with the axial direction and separating from a pressing member (positioning process). Japanese Patent Application Laid-Open. No. 2013-246247 discusses a configuration corresponding to the insertion process and the positioning process, i.e., a configuration of a pressed portion of a development container pressed by a pressing member in a state where the pressing member and a cartridge have been mounted.
More specifically, it the configuration discussed in Japanese Patent Application Laid-Open No. 2013-246247, the pressed portion is disposed at a protruding portion protruding from the development container and positioned at a position distant to some extent from the root of the protruding portion protruding from the development container.
In the configuration discussed in Japanese Patent Application Laid-Open No. 2013-246247, it is necessary that the pressed portion does not interfere with the apparatus main body in the insertion process and that the pressing member can press the pressed portion even if the cartridge moves in the direction away from the pressing member in the positioning process. Therefore, it is necessary to provide the pressed portion at a position distant to some extent from the root of the protruding portion. Therefore, if the pressing member presses the pressed portion with the cartridge mounted, the protruding portion of the development container may be elastically deformed or creep-deformed when the pressed portion is pressed by the pressing member. Such a deformation of the protruding portion may possibly cause the loss of the amount of separation of the developing roller from the photosensitive drum when separating the developing roller from the photosensitive drum or the loss of the amount of contact pressure of the developing roller onto the photosensitive drum when bringing the developing roller into contact with the photosensitive drum.
When the pressing member is moved by a predetermined amount while pressing the pressed portion, the protruding portion of the development container is deformed and therefore the amount of separation of the developing roller from the photosensitive drum becomes smaller than the separation amount in a case where the development container is a rigid body. The loss of the separation amount refers to this amount of reduction in the separation amount. Therefore, to secure a predetermined separation amount, it has been necessary to increase the moving amount of the pressing member for separating the developing roller from the photosensitive drum taking the loss of the separation amount into consideration.
When the pressing member moved by a predetermined amount while pressing the pressed portion, the protruding portion of the development container is deformed and therefore the contact pressure for bringing the developing roller into contact with the photosensitive drum becomes smaller than the contact pressure in a case where the development container is a rigid body. The loss of the contact pressure refers to this amount of reduction in the contact pressure. Therefore, to secure a predetermined contact pressure, it has been necessary to increase the moving amount of the pressing member for bringing the developing roller into contact with the photosensitive drum taking the loss of the contact pressure into consideration.
To gain the moving amount of the pressing member required to ensure the predetermined separation amount or the predetermined contact pressure taking the above-described losses into consideration, a space which is large to some extent needs to be allocated to allow the pressing member to move in the apparatus main body. Therefore, it has been difficult to downsize the apparatus main body.